A.T. Robertson Commentary John 7:19

"Did not Moses give you the law, and [yet] none of you doeth the law? Why seek ye to kill me?" — John 7:19 (ASV)

And yet (κα). Clear use of κα in the adversative sense of "and yet" or "but." They marvelled at Christ's "ignorance" and boasted of their own knowledge of the law of Moses. And yet they violated that law by not practising it.

Why seek ye to kill me? (Τ με ζητειτε αποκτειναι; ). A sudden and startling question as an illustration of their failure to do the law of Moses. Jesus had previously known (5:39,45-47) that the Jews really rejected the teaching of Moses while professing to believe it. On that very occasion they had sought to kill him (5:18), the very language used here. Apparently he had not been to Jerusalem since then. He undoubtedly alludes to their conduct then and charges them with the same purpose now.